Recently, products in which a π-conjugated electrically conductive polymer such as polypyrrole, polythiophene and polyaniline is used as an antistatic agent, a transparent conductive film or an electrode of a capacitor are developed.
Generally, a π-conjugated electrically conductive polymer in which the main chain is composed with a conjugated system containing π electrons is an insoluble solid powder even when a dopant is doped to the polymer. Consequently, it is difficult to uniformly form a coating containing a π-conjugated electrically conductive polymer on the surface of a substrate by applying the polymer.
A method in which a π-conjugated electrically conductive polymer is coordinated with a polyanion so that the polymer can be dispersed in solvent to apply the polymer on a substrate is proposed.
For example, in Patent Document 1, in order to increase dispersity in water, a method in which dispersion liquid of poly(3,4-dialkoxythiophene) can be obtained by chemical oxidative polymerization of 3,4-dialkoxythiophene using an oxidant in the presence of polystyrenesulfonate having a molecular weight of 2,000 to 500,000.
However, the electroconductive coating formed from the dispersion liquid described in Patent Document 1 has a problem in that electrical conductivity, heat resistance, moist-heat resistance, and substrate adhesion property are inadequate.
To solve the problem, the present inventors propose a method in which a specific compound for forming a crosslinking point is contained in the dispersion liquid (Patent Document 2).